1852.J 



PORTABLE LIFTING MACHINE. 



S? 



Annexed is a summaiy of the cast and wrought iron used in 

 the bridge : — 



Tons. cwte. qrs. 

 Wrouglit iron, in tli'ee spans of 100 feet eacli, double line 277 

 Wrought iron in the girders, floor-bearers, and other work 



of the main span of 300 feet, double line - - 

 Two wrought iron tubes, each 312 feet long - - 

 ■Wrought iron beam on the standard to support the tubes 

 Vertical trusses --..•••...-•. 37 

 Tie girders to connect the caps of columns - - - 

 Saspending links in main chains and diagonals • 

 Saddles at points of suspension rollers - - - - 



Adjusting screws -..••..... 



Eollers of main tube ......... 



Rollers of girders ---.--.-•. 

 BolU 



Total wrought iron •• 1831 22 



Tons. cwtB. qra. 

 Cast iron bed-plates for trusses -....-.. 24 61 

 standard 128 60 



•' caps for columns and parapets ..... 21 00 

 " cylinders in the supporting piers ..... 830 



Total cast iron 1003 12 1 



To;is. cwts. qrs. 



Wrought iron 1231 2 3 > gg, , , , , 



Cast iron 1003 12 1 I ^•^•** '* * 



Masonry in abutment and pier, 3240 cubic yards. 

 Total estimated cost of the Bridge when entirely completed, £65,420. 

 The Bridge has been visited by a great number of engineers 



from the Continent and the East Indies ; indeed, it is only by a 

 personal inspection that the numerous ingenious arrangements 

 can be understood. 



The whole seems, when finished, to be very simple; yet 

 engineers will fully enter into the complexity of the design, and 

 the minute and carefully propoi'tioned scantlings given to every 

 part. We would specially call their attention to the cast-iron ring 

 or circle attached to the ends of the tube to prevent collapse ; to 

 the wedges introduced undei the vertical trusses to adjust the 

 exact tension upon the chain ; to the curve given to the tubes 

 themselves, increasing their strength; and to the roller-boxes 

 under the vertical trusses, by which means the road girders are 

 maintained in a position to expand or contract independently of 

 the movements of the main tubes. 



The private trial of the Bridge took place on Wednesday, the 

 14th instant, and was described in our Journal of last week. 

 The public opening of the Bridge took place on Monday last, the 

 19th. The fii-st train that passed over was the six o'clock train 

 from Swansea. To show the public utility of this great work, it 

 may be mentioned that two years ago the jom-ney from London 

 to Swansea, partly by railwajf and partly by coach, crossing by a 

 ferry-boat the dangerous passage of the Severn at Beachley, 

 occupied 15 hours. The express trains are now timed to 

 perform the same distance (216 miles) with ease and comfort 

 in five hours. — Illustrated London Neios. 



Portable Lifting Machine. 



PoKTABLE Lifting Machine.- 



Figl. 



-Scale, Oxe-Fourth. 



The object of this machine, which is the invention of Mr. Long, 

 hydrometer maker, Loudon, is to obtain, in a portable and simple 

 form, the means of multiplying the power of a man to a very great 



extent, for the purpose of Hfting weights, (fee, without the draw- 

 back of heavy friction and wear to which some lifting machines 

 are liable, such as those in which an endless screw works into a 

 toothed wheel. The construction is shown in the annexed 

 engravings, figs 1 and 2. A, is a wheel on which eleven pins 

 B H I, are fixed in the form of teeth, with a friction roller fitted 

 upon each pin. The circular plate C C, is fixed at right angles 

 to this wheel, upon the shaft of the winch D, to which the 

 manual power is applied. On this plate is east the spiral pro- 

 jecting piece E F G, which makes rather more than one turn 

 upon the plate. This spiral is engaged with the pins B H, on 

 the firet wheel, and the difference in the amount of eccentricity 

 of the two ends of the spiral is ecjual to the pitch or distance 

 between the pins; so that when the plate C, and spiral are turned 

 round one revolution by the handle, the wheel A, is driven round 

 the distance of one pin or tooth. 



The dri\'ing ftwe of the spiral has a varying be\il, adjusted so 

 as to bear fairly and uniformly upon each pin in succession 

 throughout the entire revolution, as the pin varies its inclination 

 from B to H; the next pin above, I, being then brought down 

 into the position B. The thickness of the spiral, as shown at G 

 nearly fills the space between the two pins at all times, preventing 

 any slip, and the upper piu is engaged a short distance before the 

 lower one is released. The friction I'oller upon the pin turns 

 round during the motion, rolUng, with little friction, along the 

 inner surface of the spiral, which forms an inclined plane, with 

 an inclination of about 1 in 7. 



A pinion fixed on the wheel A, is geared into one of three 

 times the diameter on the third, shaft, ^ upon which is fixed the 

 drum L, for winding up the rope or chain attached to the weight 

 to be lifted. The leverage of the spiral and first wheel being 1 1 

 to 1, and that of the spur gearing 3 to 11, makes a power of 33 

 to 1, and the radius of the winch-handle and of the drum being 

 6 to 1, the total increase of power obtained by the machine is 

 200 to 1 nearly; or one man exerting a power of -J-cwt. at the 

 winch could lift five tons, including the friction. 



This machine has the advantage of reducing the friction, in 



